What is the function of citrate synthase in the Citric Acid Cycle?

Citrate synthase plays a crucial role in the Citric Acid Cycle as it catalyzes the synthesis of citrate from acetyl-CoA and oxaloacetate. This reaction represents one of the first steps in the cycle and is pivotal for initiating the sequence of reactions that lead to the production of energy through the oxidation of metabolites.

During this reaction, acetyl-CoA, which carries a two-carbon unit, condenses with oxaloacetate, a four-carbon molecule, to form citrate, a six-carbon compound. This step not only marks the beginning of the cycle but also sets the stage for subsequent reactions that ultimately lead to the release of energy stored in the chemical bonds of acetyl-CoA.

The activity of citrate synthase is vital because it regulates the flow of substrates into the Citric Acid Cycle, making it a key control point in cellular metabolism. By facilitating this condensation reaction, citrate synthase ensures that the cycle can proceed, allowing for the continued production of NADH and FADH2, which are essential for ATP generation through oxidative phosphorylation.